Near misses: Murphy´s law is wrong [design engineering]

It has been said that you learn more from your mistakes than from your successes. Best of all is when you can learn from someone else\´s mistakes. So this article looks at three test cases. (1) What did engineers and computer scientists learn about product development when the Space Shuttle Challenger exploded? (2) What did you resolve to do better after the Hubble Space Telescope error? (3) What did you learn from the Mars Climate Orbiter error? In all three of these cases, there is plenty of learning to be had for anyone doing design in any field. Murphy\´s law ("If anything can go wrong, it will go wrong") is clearly incorrect. When the Challenger exploded, the problem was quickly traced to the O-rings in the solid rocket boosters because those O-rings were already under suspicion due to charring and hot-gas "blow-by" in half of the previous 25 Shuttle missions. Murphy\´s law implies those earlier flights should have blown up, but the lesson embedded in those near misses went unheeded. NASA says there were even hints during the Mars Climate Orbiter flight that something was wrong. Perkin Elmer ignored several indications that something was wrong with Hubble\´s main mirror. Near misses are nature\´s way of telling us that something\´s wrong and we\´d better fix it fast. If we ignore them, that\´s when Murphy comes calling